The present invention relates to a photographing apparatus and a method of removing foreign substances, and more particularly, to a photographing apparatus including a foreign substance-removing unit for preventing foreign substances from being attached to an imaging device, and a method of removing foreign substances.
Recently, photographing apparatuses such as digital still cameras or video cameras have been widely supplied.
The photographing apparatuses are now capable of providing high quality images due to imaging devices such as a charge-coupled device (CCD) having a large number of pixels. Also, recently, a lens interchangeable photographing apparatus, in which a single-lens reflex finder is detachably mounted on a main body of the lens interchangeable photographing apparatus so that a user can select an optical system (lens) according to necessity, has been widely supplied.
When a lens is separated from the main body of a lens interchangeable photographing apparatus, foreign substances floating in the air may penetrate into the main body of the lens interchangeable photographing apparatus. Also, instruments such as a shutter and an iris that mechanically operate are included inside the main body of the photographing apparatus, and as the instruments operate, foreign substances may be generated.
Therefore, a foreign substance-removing unit that prevents attachment of foreign substances to an imaging device is installed on an imaging plane side of the imaging device of a photographing apparatus. In general, the foreign substance-removing unit has a structure in which a vibration member is vibrated using a piezoelectric element.
The foreign substance-removing unit vibrates the vibration member at a resonance frequency of the vibration member in order to generate sufficient vibration for removing foreign substances. Since the resonance frequency is a standing wave, dust is not removed in nodes of the vibration member, which are hardly shifted during the vibration of the vibration member.
To address this problem, a device for vibrating a vibration member at two or more resonance frequencies has been disclosed in Japanese Patent No. 3727903, or a controlling method for vibrating a vibration member while sequentially changing a frequency by sweeping the frequency in order to, with certainty, vibrate the vibration member at a resonance frequency has been disclosed in Japanese Patent Laid-Open Gazette No. 2004-48665.
Also, in Japanese Patent Laid-Open Gazette No. 2008-3165, a method, in which a vibration member is vibrated at a frequency band including a first resonance frequency and then at another frequency band including a second resonance frequency that is not continuous to the first resonance frequency, is disclosed.
However, in the inventions disclosed in Japanese Patent No. 3727903, Japanese Patent Laid-Open Gazette No. 2004-48665, or Japanese Patent Laid-Open Gazette No. 2008-3165, the vibration member is sequentially vibrated at a plurality of resonance frequencies, and thus it takes a lot of time to perform an operation of removing foreign substances by vibrating the vibration member at all of the resonance frequencies.
Also, in the method disclosed in Japanese Patent Laid-Open Gazette No. 2004-48665, in which a vibration member is vibrated while sequentially changing a frequency by sweeping the frequency, the vibration member is hardly vibrated at points other than a resonance point of a piezoelectric element. Moreover, even though the foreign substances are hardly removed at the above points other than the resonance point of a piezoelectric element, the vibration member continues to vibrate, thereby wasting power.